1. Field of the Invention
This invention relates to an imaging system useful in medical and industrial x-ray imaging, including classical and digital radiography, and CT scanning. The imaging system of the present invention provides an increased spatial resolution over imaging systems of the prior art by angulating an x-ray detector or detector array with respect to a radiation source.
2. Description of the Prior Art
A number of prior art systems and devices exist for x-ray imaging. The resolution of prior art imaging systems is limited by a variety of different factors. In conventional x-ray detectors, resolution limitations arise from the ranges of electrons and reabsorbed, scattered x-ray photons released in the x-ray detection media.
In imaging systems which use x-ray intensifying screens and in image intensifiers, further resolution limitations arise from lateral light propagation in the detection media. In clear intensifying screen plus lens imaging systems, resolution limitations arise from optical aberrations which depend upon the x-ray absorption position.
In discrete scintillator plus photodetector systems, resolution limitations arise from finite cell dimensions. In gas ionization detectors, resolution limitations arise from finite cell or electrode size and from effects which disperse the ion positions during collection.
The apparatus of the present invention provides significantly improved resolution over x-ray imaging systems of the prior art. The x-ray imaging system of the present invention further provides information on the energy of detected photons. Such information is useful in differentiating component tissues and other materials in the subject based, not only on, gross x-ray absorption, but also on absorption vs. photon energy. The energy discriminating capabilities of the present system provide information allowing isolation of subject components according to atomic number, thereby allowing for chemical identification of components such as calcium, water, fat, and any contrast agents used.
The present invention is directed toward an imaging system for providing an image of a target body. The invention comprises a radiation source capable of emitting a beam of electromagnetic radiation. The source is aimed at a target body. Depending upon the size of the target body, the invention may also comprise a collimator positioned between the radiation source and a target body so as to control the lateral dimension of the beam within a preselected range.
The invention further comprises a linear first detector array comprising a multiplicity of detectors. The detector array may comprise a multiplicity of scintillator crystals and photodiodes. Alternatively, the detector may comprise a continuous detection medium. The first detector array is oriented such that a radiation beam from a radiation source strikes the detector array at a tilt angle sufficient to define a field of view of sufficient size to image a target body. Because of the angulation of the detector array, the detector cells appear closer in projection as viewed from the radiation source, thereby proportionately increasing the spatial resolution. The detector array is capable of generating a signal indicative of integrated or counting data.
The invention further comprises a signal receiving and storage device connected to receive a signal indicative of integrated or counting data. The signal receiving and storage device is further capable of storing integrated or counting data from the detector array.
The invention further comprises an image display system coupled to the receiving and storage device and capable of displaying images derived from integrated or counting data in the receiving and storage device.